Sensing system and method for motion-controlled foot unit

ABSTRACT

A system and method for sensing movement of a device associated with a limb. In one example, a prosthetic or orthotic system includes a sensor assembly configured to measure movement of a component of the system in a single direction while substantially isolating negative effects of forces and/or loads in other directions. For instance, the sensor assembly may be advantageously coupled to a pivot assembly configured to substantially mimic a natural ankle joint. The sensor assembly may monitor rotation of a foot unit about an axis of a pivot pin of the pivot assembly and disregard other movements and/or forces. For example, the sensor assembly may include a potentiometer that detects rotation of an associated elongated bellow portion about the axis, wherein the bellow portion includes a plurality of ridges configured to substantially eliminate effects of radial and/or axial forces.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Preferred embodiments of this invention relate to sensing systems andmethods for a motion-controlled limb and, in particular, anankle-motion-controlled foot.

2. Description of the Related Art

Millions of individuals worldwide rely on prosthetic and/or orthoticdevices to compensate for disabilities, such as amputation ordebilitation, and to assist in the rehabilitation of injured limbs.Orthotic devices include external apparatuses used to support, align,prevent, protect, correct deformities of, or improve the function ofmovable parts of the body. Prosthetic devices include apparatuses usedas artificial substitutes for a missing body part, such as an arm orleg.

The number of disabled persons and amputees is increasing each year asthe average age of individuals increases, as does the prevalence ofdebilitating diseases such as diabetes. As a result, the need forprosthetic and orthotic devices is also increasing. Conventionalorthoses are often used to support a joint, such as an ankle or a knee,of an individual, and movement of the orthosis is generally based solelyon the energy expenditure of the user. Some conventional prostheses areequipped with basic controllers that artificially mobilize the jointswithout any interaction from the amputee and are capable of generatingonly basic motions. Such basic controllers do not take intoconsideration the dynamic conditions of the working environment. Thepassive nature of these conventional prosthetic and orthotic devicestypically leads to movement instability, high energy expenditure on thepart of the disabled person or amputee, gait deviations and other short-and long-term negative effects. This is especially true for leg orthosesand prostheses.

Furthermore, some conventional prosthetic and orthotic devices have atleast one sensor associated therewith that is used to monitor movementof the prosthetic/orthotic device or the individual. Such sensors,however, are often subjected to various forces and/or loads that mayaffect the sensors' readings.

SUMMARY OF THE INVENTION

Accordingly, one embodiment of the invention includes a prosthetic ororthotic system that is self-powered and that mimics the naturalmovement of a healthy limb, and in particular, the movement of a healthyankle. Another embodiment of the invention includes a sensor system anda control system that manage the motion of the prosthetic or orthoticsystem so as to facilitate movement by the disabled person or amputee.

One embodiment of the invention includes a system associated with themovement of a limb. In one embodiment, the system comprises a foot unit;an attachment member having an upper end and a lower end, wherein thelower end is pivotably attached to a first location on the foot unit;and an actuator operatively coupled to the foot unit and to theattachment member, wherein the actuator is configured to actively adjustan angle between the attachment member and the foot unit. For example,the foot unit may be a prosthetic or orthotic device.

Another embodiment of the invention includes a prosthetic system formimicking the natural movement of an ankle. In one embodiment, theprosthetic system comprises a prosthetic foot; a pivot assembly attachedto a first position on the prosthetic foot, wherein the first positionis near a natural ankle location of the prosthetic foot; a lower limbmember extending in a tibial direction, the lower limb member having anupper end and a lower end, wherein the lower end of the lower limbmember is operatively coupled to the pivot assembly; and an actuatoroperatively coupled to the prosthetic foot and to the lower limb member,wherein the actuator is configured to actively adjust an angle betweenthe lower limb member and the prosthetic foot about the pivot assembly.

One embodiment of the invention includes a method for controlling adevice associated with the movement of a limb. In one embodiment, themethod comprises monitoring with at least one sensor the movement of anactuatable device associated with a limb; generating data indicative ofsaid movement; processing the data with a processing module to determinea current state of locomotion of the actuatable device; and adjustingthe actuatable device based on the determined state of locomotion,wherein said adjusting comprises substantially mimicking the movement ofa healthy ankle. For example, the actuatable device may be a prosthesisor an orthosis.

Another embodiment of the invention includes a method for controlling aprosthetic ankle device. In one embodiment, the method comprisesmonitoring with at least one sensor the movement of an actuatableprosthetic ankle device, wherein the at least one sensor generates dataindicative of the movement of the prosthetic ankle device; receiving andprocessing the data with a control module to determine a current stateof locomotion of the actuatable prosthetic ankle device; outputting withthe control module at least one control signal based on the determinedstate of locomotion; and adjusting the actuatable prosthetic ankledevice based at least upon the control signal, wherein said adjustingcomprises substantially mimicking the movement of a healthy ankle.

In one embodiment, a prosthetic or orthotic system is provided having anankle-motion-controlled foot. The prosthetic or orthotic systemcomprises, among other things, a lower limb member, an actuator, and afoot unit. The actuator is configured to mimic the motion of an ankle byadjusting the angle between the lower limb member and the foot unit. Theprosthetic or orthotic system also comprises an attachment portion thatfacilitates coupling of the lower limb member to another prosthetic ororthotic member, to the stump of an amputee, or to another component.The prosthetic or orthotic system may also comprise a rechargeablebattery to provide power to the actuator or other components of thesystem. Embodiments of the invention include systems for bothtranstibial and transfemoral amputees.

In another embodiment of the invention, the prosthetic or orthoticsystem comprises a sensor system that is used to capture informationregarding the position and movement of the prosthetic or orthoticdevice. This information may be processed in real- time so as to predictappropriate movements for the prosthetic or orthotic device and toadjust the prosthetic or orthotic device accordingly.

In one embodiment of the invention, a system architecture is providedhaving a sensor module, a central processing unit, a memory, an externalinterface, a control drive module, an actuator, and an ankle device. Thesystem architecture may receive instructions and/or data from externalsources, such as a user or an electronic device, through the externalinterface.

In one embodiment, a control system may also be provided that managesthe movement of the orthosis or the prosthesis. In one embodiment, thecontrol system manages the movement of an actuator, such as a screwmotor. Such motion control provides for movement by the user up inclinedsurfaces, down declines, or on stairs. In one embodiment, the controlsystem may be configured to monitor through sensors the movements of ahealthy limb and use the measurements to control the movement of theprosthesis or orthosis. The control system may also manage the dampingof the actuator or other portions of the orthosis or prosthesis.

In one embodiment, a method is provided for controlling actuation of aprosthetic or orthotic device. The method comprises providing one ormore sensors on an actuatable prosthetic or orthotic device. Datareceived from the sensors is processed and is used to determine thecurrent state of locomotion for the prosthetic device. A processingunit, using at least a portion of the data received from the sensors,then predicts movement of the prosthetic or orthotic device. In oneembodiment, a prosthetic ankle is provided that mimics the movement of ahealthy ankle. The one or more sensors may comprise, for example,gyroscopes and/or accelerometers. In another embodiment of theinvention, adjustments are not made to the actuatable prosthetic ororthotic device unless the locomotion type of the user is determined bythe processing unit to have a security factor above a predeterminedthreshold value.

In another embodiment, a method is provided for identifying motion of anorthotic or prosthetic device. The method comprises receiving data fromone or more sensors placed on an orthotic or prosthetic device while thedevice is moving. A waveform is generated from the data received by thesensors. A specific motion for the orthotic or prosthetic device isidentified by correlating the waveform with known waveforms forparticular types of motion. For example, known waveforms may be inputtedby a user or downloaded from an external device or system. The waveformsmay also be stored in a memory on the prosthetic or orthotic device.

In another embodiment, a method is provided for actuating an ankle-assisting device. The device is actuated by providing a computer controlto provide relative motion between a first and a second portion of thedevice. In one embodiment, the device is an orthosis. In anotherembodiment, the device is a prosthesis. In one embodiment, the computercontrol predicts future motion of the device. In another embodiment, thecomputer control receives input from at least one sensor module thatreceives information regarding environmental variables and/or themovement or position of the prosthetic or orthotic device. In anotherembodiment, the computer control receives input from at least one sensormodule that receives information regarding the movement or position of ahealthy limb.

One embodiment of the invention includes a device configured to beattached to a limb. The device comprises a first portion and a secondportion, the first and second portions being moveable relative to eachother to mimic a natural human joint. The device also comprises anactuator coupling the first and second portions together and configuredto adjust the angle between the first and second portions. The actuatorcomprises a rotor operatively coupled to a stator and a motor configuredto rotate the rotor, wherein the actuator is selectively locked during adesired phase in a gait cycle.

Another embodiment of the invention includes a device configured to beattached to a limb. The device comprises a first portion and a secondportion, the first and second portions being moveable relative to eachother to mimic a natural human joint. The device also comprises anactuator coupling the first and second portions together and configuredto adjust the angle between the first and second portions. The actuatorcomprises a rotor operatively coupled to a stator and a motor configuredto rotate the rotor. The device also comprises means for minimizingfriction against the rotor.

Still another embodiment of the invention includes a device configuredto be attached to a limb. The device comprises a first portion and asecond portion, the first and second portions being moveable relative toeach other to mimic a natural human joint. The device also comprises anactuator coupling the first and second portions together and configuredto adjust the angle between the first and second portions. The actuatorcomprises a rotor operatively coupled to a stator and a motor configuredto rotate the rotor, wherein the motor is disposed about the rotor.

Another embodiment of the invention includes a prosthetic deviceconfigured to be attached to a limb. The device comprises a prostheticfoot and a pivot assembly attached to the prosthetic foot, the pivotassembly mimicking a natural human ankle joint. The device alsocomprises a support member having an upper end and a lower end, whereinthe lower end of the support member is operatively coupled to the pivotassembly. The prosthetic device also comprises an actuator operativelycoupled to the prosthetic foot and the support member, the actuatorconfigured to adjust an angle between the support member and theprosthetic foot about the pivot assembly, wherein the actuator isselectively locked during a desired phase of a gait cycle of theprosthetic foot.

In still another embodiment, an actuator is provided, comprising anelongate member extending about a major axis of the actuator. Theactuator also comprises a rotor rotatably coupled to the elongate memberand a stator operatively coupled to the rotor. At least one magnet isdisposed between the rotor and the stator, the magnet configured toapply a magnetic force between the rotor and the stator. The actuatoralso comprises a motor configured to rotate the rotor relative to theelongate member, wherein the at least one magnet is configured tominimize friction between the rotor and the stator.

In another embodiment of the invention, an actuator is provided,comprising an elongate member extending about a major axis of theactuator. The actuator also comprises a rotor rotatably coupled to theelongate member and a stator operatively coupled to the rotor. A ballbearing is disposed between the rotor and the stator. The actuator alsocomprises a motor configured to rotate the rotor relative to theelongate member, wherein the ball bearing is configured to minimizefriction between the rotor and the stator.

In yet another embodiment of the invention, an actuator is provided,comprising an elongate member extending about a major axis of theactuator. A rotor is rotatably coupled to the elongate member and astator operatively coupled to the rotor. The actuator also comprises amotor disposed about the rotor and configured to rotate the rotorrelative to the elongate member.

In another embodiment, an actuator is provided, comprising an elongatemember extending about a major axis of the actuator. The actuator alsocomprises a rotor rotatably coupled to the elongate member, a retainerdisposed about the rotor, and a stator operatively coupled to the rotor.A motor is configured to rotate the rotor relative to the elongatemember, wherein the rotor and the retainer selectively engage to inhibitrotation of the rotor.

In another embodiment, a method of operating a prosthetic deviceattached to a limb is provided. The method comprises providing aprosthetic device configured to attach to a limb, the device mimicking anatural human joint and having a first portion and a second portion, theportions moveable relative to each other about the joint. The methodalso comprises providing an actuator coupled to the first portion andthe second portion, adjusting an angle between the first portion and thesecond portion and selectively locking the actuator during a desiredphase of a gait cycle.

In still another embodiment, a method of operating a prosthetic deviceattached to a limb is provided. The method comprises providing aprosthetic device configured to attach to a limb, the device mimicking anatural human joint and having a first portion and a second portion, theportions moveable relative to each other about the joint. The methodalso comprises providing an actuator coupled to the first portion andthe second portion, adjusting an angle between the first portion and thesecond portion and actively minimizing friction against a rotor of theactuator during a desired phase in a gait cycle.

In another embodiment, a system is disclosed for sensing a rotationalmovement of a lower-limb prosthetic device. The system includes aprosthetic foot and an attachment member having an upper end and a lowerend. The system also includes a pivot assembly rotatably coupling thelower end of the attachment member to the prosthetic foot to allow forrotation of the prosthetic foot about a pivot axis extending through thepivot assembly, wherein the pivot assembly is configured tosubstantially mimic a natural ankle joint The system further includes asensor assembly coupled to the pivot assembly and configured to detectthe rotation of the prosthetic foot about the pivot axis, wherein atleast a portion of the sensor assembly is configured to rotate about thepivot axis and is securely positioned along the pivot axis tosubstantially eliminate other movement.

In another embodiment, a system is disclosed for sensing a rotationalmovement of a device associated with a limb. The system includes a footunit and an attachment member having an upper end and a lower end. Thesystem also includes a pivot assembly rotatably coupling the lower endof the attachment member to the foot unit to allow for rotation of thefoot unit about an axis extending through the pivot assembly, whereinthe pivot assembly is configured to substantially mimic a natural anklejoint. The system further includes a sensor assembly coupled to thepivot assembly and configured to detect the rotation of the foot unitabout the axis and to substantially neglect axial and radial movement ofthe foot unit with respect to the axis.

In another embodiment, a system is disclosed for sensing a rotationalmovement of a device associated with a lower limb. The system includes afoot means for contacting a ground surface and a means for attaching thefoot means to a patient. The system also includes a means for pivotablycoupling the foot means to a lower end of the means for attaching toallow for rotation of the foot means about an axis extending through themeans for pivotably coupling, wherein the means for pivotably couplingsubstantially mimics an ankle joint. The system further includes a meansfor sensing coupled to the means for pivotably coupling, the means forsensing further configured to detect the rotation of the foot meansabout the axis and to substantially neglect axial and radial movement ofthe foot means with respect to the axis.

For purposes of summarizing the invention, certain aspects, advantagesand novel features of the invention have been described herein. It is tobe understood that not necessarily all such advantages may be achievedin accordance with any particular embodiment of the invention. Thus, theinvention may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other advantages as may be taught or suggestedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a lower limb prosthesis having anankle-motion-controlled foot unit according to one embodiment of theinvention.

FIG. 2 is a perspective view of the lower limb prosthesis of FIG. 1,wherein a cover is removed to show inner components of the prosthesis.

FIG. 3 is a side view of the lower limb prosthesis of FIG. 2.

FIG. 4 is a rear view of the lower limb prosthesis of FIG. 2.

FIG. 5 is a side view of the lower limb prosthesis of FIG. 1 with thecover shown partially removed, wherein the ankle-motion-controlled footis adjusted to accommodate an incline.

FIG. 6 is a side view of a lower limb prosthesis of FIG. 5, wherein theankle-motion-controlled foot is adjusted to accommodate a decline.

FIG. 7 is a schematic drawing indicating the correlation between anankle pivot point on an exemplifying embodiment of a prosthetic footunit with the natural ankle joint of a human foot.

FIG. 8 is a graph depicting the range of ankle motion of an exemplifyingembodiment of a prosthetic or orthotic system during one full stride ona level surface.

FIG. 9 is a block diagram of an exemplifying embodiment of a controlsystem architecture of a prosthetic or orthotic system having anankle-motion-controlled foot.

FIG. 10 is a table illustrating control signals usable to adjust theankle angle of a prosthetic or orthotic system according to oneembodiment of the invention.

FIG. 11 is a graph depicting an exemplifying embodiment of therelationship between the control of a prosthetic or orthotic system andthe motion of a corresponding sound limb.

FIG. 12A is a perspective view of another embodiment of a lower limbprosthesis.

FIG. 12B is a side view of the lower limb prosthesis of FIG. 12A.

FIG. 12C is a cross-sectional view of the lower limb prosthesis of FIG.12B along plane M-M.

FIG. 13 is a perspective view of one embodiment of an actuator which maybe used with the lower limb prosthesis of FIG. 12A.

FIG. 14 is a side-view of the actuator of FIG. 13.

FIG. 15 is a rear view of the actuator of FIG. 13.

FIG. 16 is a top view of the actuator of FIG. 13.

FIG. 17 is a cross-sectional side view of the actuator of FIG. 13.

FIG. 18 is an exploded view of the actuator of FIG. 13.

FIG. 19 is a flow chart illustrating different phases of motion of theprosthesis shown in FIG. 12A.

FIG. 20 is a disassembled view of a lower limb prosthesis having anankle-motion-controlled foot unit according to another embodiment of theinvention.

FIG. 21 is a disassembled view of a sensor assembly usable with thelower limb prosthesis of FIG. 20.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Some preferred embodiments of the invention described herein relategenerally to prosthetic and orthotic systems and, in particular, toprosthetic and orthotic devices having an ankle-motion-controlled foot.While the description sets forth various embodiment-specific details, itwill be appreciated that the description is illustrative only and shouldnot be construed in any way as limiting the invention. Furthermore,various applications of the invention, and modifications thereto, whichmay occur to those who are skilled in the art, are also encompassed bythe general concepts described herein.

The features of the system and method will now be described withreference to the drawings summarized above. Throughout the drawings,reference numbers are re-used to indicate correspondence betweenreferenced elements. The drawings, associated descriptions, and specificimplementation are provided to illustrate embodiments of the inventionand not to limit the scope of the invention.

The terms “prosthetic” and “prosthesis” as used herein are broad termsand are used in their ordinary sense and refer to, without limitation,any system, device or apparatus usable as an artificial substitute orsupport for a body part.

The term “orthotic” and “orthosis” as used herein are broad terms andare used in their ordinary sense and refer to, without limitation, anysystem, device or apparatus usable to support, align, prevent, protect,correct deformities of, immobilize, or improve the function of parts ofthe body, such as joints and/or limbs.

The term “ankle device” as used herein is a broad term and is used inits ordinary sense and relates to any prosthetic, orthotic orankle-assisting device.

The term “transtibial” as used herein is a broad term and is used in itsordinary sense and relates to without limitation any plane, direction,location, or cross-section that is located at or below a knee joint of abody, including artificial knee joints.

The term “transfemoral” as used herein is a broad term and is used inits ordinary sense and relates to without limitation any plane,direction, location, or cross-section that is located at or above a kneejoint of a body, including artificial knee joints.

The term “sagittal” as used herein is a broad term and is used in itsordinary sense and relates to any description, location, or directionrelating to, situated in, or being in or near the median plane (i.e.,the plane divides the body lengthwise into right and left halves) of thebody or any plane parallel or approximately parallel thereto. A“sagittal plane” may also refer to any vertical anterior to posteriorplane that passes through the body parallel or approximately parallel tothe median plane and that divides the body into equal or unequal rightand left sections.

The term “coronal” as used herein is a broad term and is used in itsordinary sense and relates to any description, location, or directionrelating to, situated in, or being in or near the plane that passesthrough the long axis of the body. A “coronal plane”may also refer toany plane that passes vertically or approximately vertically through thebody and is perpendicular or approximately perpendicular to the medianplane and that divides the body into anterior and posterior sections.

FIG. 1 illustrates one embodiment of a lower limb prosthesis 100 havingan ankle-motion-controlled foot with an attachment member. Theprosthesis 100 comprises an attachment member, in the form of a lowerlimb member 102, operatively coupled to a foot unit 104. As used herein,the term “attachment member” is a broad term and is used in its ordinarysense and in a prosthetic foot embodiment relates to, withoutlimitation, any member that attaches either directly or indirectly tothe foot unit 104 and is moveable in relation thereto, for example by apivoting motion, and is used to attach the prosthesis 100 to a stump orintermediate prosthesis. As illustrated, the attachment member may takethe form of a lower limb member in an ankle-prosthesis embodiment. Inother embodiments, for example an orthotic embodiment, the attachmentmember may be used to attach to and support a body part, such as with abrace, which also is moveably connected to a second member, such as afoot unit, which would also attach to and support a body part, such asthe foot. In one embodiment, the lower limb member 102 is a generallyelongated member with a main longitudinal axis that extends inapproximately a tibial direction, that is, a direction that extendsgenerally along the axis of a natural tibia bone. For example, FIG. 1depicts the lower limb member 102 as being a generally verticalorientation.

In another embodiment, the lower limb member 102 may comprise multiplesections. For example, the lower limb member 102 may comprise twoelongated sections that extend approximately parallel in a tibialdirection and that are connected together. In another embodiment, thelower limb member 102 comprises a two-sided chamber having twosubstantially symmetrical parts to form a partially enclosed housing. Inanother embodiment, the lower limb member 102 may comprise a hollowmember, such as a tube-like structure. In other embodiments, the lowerlimb member 102 may comprise elongated flat portions or roundedportions. In yet other embodiments, the structure of the lower limbmember 102 is not elongated. For example, the lower limb member 102 maycomprise a generally circular, cylindrical, half-circular, dome-shaped,oval or rectangular structure. One example of a possible lower limbmember is the ankle module and the structures described in U.S. patentapplication Ser. No. 10/742,455, filed Dec. 18, 2003, and entitled“PROSTHETIC FOOT WITH ROCKER MEMBER,” the entirety of which is herebyincorporated herein by reference and is to be considered as part of thisspecification.

In one embodiment, the lower limb member 102 is generally formed of amachine metal, such as aluminum, or a carbon fiber material. In otherembodiments of the invention, the lower limb member 102 may compriseother materials that are suitable for prosthetic devices. In oneembodiment, the lower limb member 102 advantageously has a heightbetween approximately 12 and 15 centimeters. In other embodiments of theinvention, the lower limb member 102 may have a height less than 12centimeters or height greater than 15 centimeters depending on the sizeof the user and/or the intended use of the prosthesis 100. For example,the lower limb member 102 may have a height of approximately 20centimeters.

In one embodiment, the prosthesis 100 is configured such that the mainlongitudinal axis of the lower limb member 102 is substantiallyperpendicular to a lower surface of the foot unit 104 when theprosthesis 100 is in a resting position. In another embodiment, thelower limb member 102 may be substantially perpendicular to a levelground surface when the foot unit 104 rests on the ground. Such aconfiguration advantageously provides a user with increased supportand/or stability.

As depicted in FIG. 1, the lower limb member 102 further comprises acover 106. The cover 106 houses and/or protects the inner components ofthe lower limb member 102. In another embodiment, the cover 106 may berounded or may be shaped in the form of a natural human leg.

The lower limb member 102 further comprises an attachment portion 108 tofacilitate coupling of the lower limb member 102. For example, asdepicted in FIG. 1, the attachment portion 108 of the lower limb member102 couples the prosthesis 100 to a pylon 110. In other embodiments ofthe invention, the attachment portion 108 may be configured to couplethe prosthesis 100 to a stump of an amputee or to another prostheticdevice. FIG. 1 also depicts a control wire 112 usable to provide powerto and/or communicate control signals to the prosthesis 100.

The foot unit 104 may comprise various types of prosthetic or orthoticfeet. As illustrated in FIG. 1, the foot unit 104 incorporates a designdescribed in Applicant's co-pending U.S. patent application Ser. No.10/642,125, entitled “LOW PROFILE PROSTHETIC FOOT,” and filed Aug. 15,2003 the entirety of which is hereby incorporated by reference and is tobe considered as part of this specification. For example, the foot unit104 may comprise a standard LP VARI-FLEX® unit available from Ossur.

In one embodiment, the foot unit 104 is configured to exert aproportional response to weight or impact levels on the foot unit 104.In addition, the foot unit 104 may comprise shock absorption forcomfortable loading of the heel and/or for returning expended energy.The foot unit 104 may comprise a full-length toe lever with enhancedflexibility so as to provide a stride length for the prosthetic limbthat mimics the stride length of the healthy limb. In addition, asdepicted in FIG. 1, the foot unit 104 may comprise a split-toeconfiguration, which facilitates movement on uneven terrain. The footunit 104 may also include a cosmesis or a foot cover such as, forexample, a standard Flex-Foot cover available from Ossur.

FIG. 2 depicts the prosthesis 100 with the cover 106 removed. As shown,a lower end of the lower limb member 102 is coupled to the foot unit 104at a pivot assembly 114. As illustrated, the lower limb member 102 iscoupled to an ankle plate of the foot unit 104, which extends generallyrearward and upward from a toe portion of the foot unit 104. The pivotassembly 114 allows for angular movement of the foot unit 104 withrespect to the lower limb member 102. For example, in one embodiment,the pivot assembly 114 advantageously comprises at least one pivot pin.In other embodiments, the pivot assembly 114 comprises a hinge, amulti-axial configuration, a polycentric configuration, combinations ofthe same or the like. Preferably, the pivot assembly 114 is located on aportion of the foot unit 104 that is near a natural ankle location ofthe foot unit 104. In other embodiments of the invention, the pivotassembly 114 may be bolted or otherwise releasably connected to the footunit 104.

FIG. 2 further depicts the prosthesis 100 having an actuator 116. In oneembodiment, the actuator 116 advantageously provides the prosthesis 100with the necessary energy to execute angular displacements synchronizedwith the amputee's locomotion. For example, the actuator 116 may causethe foot unit 104 to move similar to a natural human foot. In oneembodiment, the lower end of the actuator 116 is coupled to the footunit 104 at a first attachment point 118. As illustrated, the footattachment point 118 is advantageously located on the upper surface ofthe foot unit 104 on a posterior portion thereof. The upper end of theactuator 116 is coupled to the lower limb member 102 at a secondattachment point 120. In one embodiment, the linear motion (or extensionand contraction) of the actuator 116 controls, or actively adjusts, theangle between the foot unit 104 and the lower limb member 102. FIG. 2depicts the actuator 116 comprising a double-screw motor, wherein themotor pushes or pulls a posterior portion of the foot unit 104 withrespect to the lower limb member 102. In other embodiments, the actuator116 comprises other mechanisms capable of actively adjusting an angle,or providing for motion between, multiple members. For example, theactuator 116 may comprise a single-screw motor, a piston cylinder-typestructure, a servomotor, a stepper motor, a rotary motor, a spring, afluid actuator, or the like. In yet other embodiments, the actuator 116may actively adjust in only one direction, the angle between the lowerlimb member 102 and the foot unit 104. In such an embodiment, the weightof the user may also be used in controlling the angle caused by and/orthe movement of the actuator 116.

FIG. 2 illustrates the actuator 116 in a posterior configuration,wherein the actuator 116 is located behind the lower limb member 102. Inother embodiments, the actuator 116 may be used in an anteriorconfiguration, wherein the actuator 116 is located in front of the lowerlimb member 102. In another embodiment of the invention, the actuator116 comprises an auto adjusting ankle structure and incorporates adesign, such as described in U.S. Pat. No. 5,957,981, the entirety ofwhich is hereby incorporated by reference and is to be considered as apart of this specification. The particular configuration or structuremay be selected to most closely imitate the movement and location of anatural human ankle joint and to facilitate insertion of the prosthesis100 into an outer cosmesis.

Furthermore, the actuator 116 is advantageously configured to operate soas to not to emit loud noises, such as intermittent noises, perceptibleby the user and/or others. The actuator 116 may also be configured tonot operate or adjust if the prosthesis 100 experiences torque, such asin the sagittal plane, that exceeds a certain level. For example, if thetorque level exceeds four Newton meters (Nm), the actuator 116 may ceaseto operate or may issue an alarm.

The actuator 116 may also be substantially enclosed within the cover 106as shown in FIG. 1 such that the portions of the actuator 116 are notvisible and/or exposed to the environment. In another embodiment, theactuator may be at least partially enclosed by the lower limb member102.

FIG. 2 further depicts control circuitry 122 usable to control theoperation of the actuator 116 and/or the foot unit 104. In oneembodiment, the control circuitry 122 comprises at least one printedcircuit board (PCB). The PCB may further comprise a microprocessor.Software may also reside on the PCB so as to perform signal processingand/or control the movement of the prosthesis 100.

In one embodiment, the prosthesis 100 includes a battery (not shown)that powers the control circuitry 122 and/or the actuator 116. In oneembodiment, the battery comprises a rechargeable lithium ion batterythat preferably has a power cycle of at least 12 to 16 hours. In yetother embodiments, the power cycle of the battery may be less than 12hours or may be more than 16 hours. In other embodiments of theinvention, the battery comprises a lithium polymer battery, fuel celltechnology, or other types of batteries or technology usable to providepower to the prosthesis 100. In yet other embodiments, the battery isremovably attached to a rear surface of the lower limb member 102, toother portions of the prosthesis 100, or is located remote theprosthesis 100. In further embodiments, the prosthesis 100 may beconnected to an external power source, such as through a wall adapter orcar adapter, to recharge the battery.

In one embodiment, the prosthesis 100 is configured to lock in a neutralposition, such as the lower limb member 102 being aligned generallyvertical relative to a level ground surface when the foot unit 104 isresting on the level ground surface, when the battery is out of power orenters a low power stage. Such locking provides for operational safety,reliability, and/or stability for a user. The prosthesis 100 may alsoprovide a battery status display that alerts the user as to the status(i.e., charge) of the battery. In another embodiment, the prosthesis 100locks into a substantially neutral position when the motion controlfunctions of the prosthesis 100 are turned off or disabled by a user.

As discussed above, a cosmesis material or other dressings may be usedwith the prosthesis 100 so as to give the prosthesis 100 a more naturallook or shape. In addition, the cosmesis, dressings, or other fillermaterial may be used to prevent contaminants, such as dirt or water,from contacting the components of the prosthesis 100.

FIG. 3 depicts a side view of the prosthesis 100 according to oneembodiment of the invention. As depicted in FIG. 3, the actuator 116further comprises a main housing 124, a lower extendable portion 126,and an upper extendable portion 128. The lower extendable portion 126couples the main housing 124 of the actuator 116 to the foot unit 104 atthe first attachment point 118. The upper extendable portion 128 couplesthe main housing 124 of the actuator 116 to the lower limb member 102 atthe second attachment point 120. During operation and active adjustmentof the prosthesis 100, the lower extendable portion 126 and/or the upperextendable portion 128 move into and/or out of the main housing 124 ofthe actuator 116 to adjust an angle between the foot unit 104 and thelower limb member 102.

For example, to increase an angle between the foot unit 104 and thelower limb member 102, the actuator 116 causes the lower extendableportion 126 and/or the upper extendable portion 128 to contract orwithdraw into the main housing 124. For example, at least one of theextendable portions 126, 128 may have a threaded surface such thatrotation in one direction (e.g., clockwise) causes the extendableportion to withdraw into the main housing 124 of the actuator. In otherembodiments, at least one of the extendable portions 126, 128 comprisesmultiple telescoping pieces such that, upon contraction, one of themultiple pieces of extendable portion contracts into another of themultiple pieces without withdrawing into the main housing 124. Likewise,to decrease an angle between the foot unit 104 and the lower limb member102, the lower extendable portion 126 and/or the upper extendableportion 128 may extend from the main housing 124.

In embodiments of the invention having an anterior configuration for theactuator 116, extension of the lower extendable portion 126 and/or theupper extendable portion 128 causes an increase in the angle between thelower limb member 102 and the foot unit 104. Likewise, a contraction ofthe lower extendable portion 126 and/or the upper extendable portion 128causes a decrease in the angle between the foot unit 104 and the lowerlimb member 102.

FIG. 4 illustrates a rear view of the prosthesis 100 depicted in FIGS.1-3. In other embodiments of the invention, the cover 106 extends aroundthe posterior portion of the prosthesis 100 to house at least a portionof the actuator 116 such that portions of the actuator 116 are notvisible and/or not exposed to the environment.

FIGS. 5 and 6 illustrate one embodiment of the prosthesis 100 as itadjusts to inclines and declines. With reference to FIG. 5, theprosthesis 100 is depicted as adjusting to an incline. In thisembodiment, the actuator 116 extends so as to decrease an angle θbetweenthe lower limb member 102 and the foot unit 104 (or “dorsiflexion”).With respect to dorsiflexion, in one embodiment, the angular range ofmotion of the prosthesis 100 is from about 0 to 10 degrees from theneutral position. Other embodiments may also facilitate exaggerateddorsiflexion during swing phase.

FIG. 6 illustrates the prosthesis 100 as it adjusts to a decline. Theactuator 116 extends so as to increase the angle θ between the lowerlimb member 102 and the foot unit 104 (or “plantarflexion”). Withrespect to plantarflexion, in one embodiment, the angular range ofmotion of the prosthesis 100 is from about 0 to 20 degrees from theneutral position. Such plantarflexion mimics natural ankle movement andprovides for greater stability to an amputee or a user. In oneembodiment, the total range of motion about the ankle pivot axis of theprosthesis 100, including both plantarflexion and dorsiflexion, isapproximately 30 degrees or more.

In addition to operating on inclines and declines, the motion-controlledfoot of the prosthesis 100 advantageously accommodates differentterrain, operates while traveling up and down stairs, and facilitateslevel ground walking. In addition, the prosthesis 100 may provide forautomatic heel height adjustability. Heel height may be measured, in oneembodiment, from an ankle portion of the lower limb member 102 to aground surface when the foot unit 104 is generally flat to the ground.For example, a user may adjust to various heel heights, such as throughpressing one or more buttons, such that the prosthesis 100 automaticallyaligns itself to the appropriate heel height. In one embodiment, theprosthesis 100 includes a plurality of predetermined heel heights. Inyet other embodiments, the prosthesis 100 may automatically adjust theheel height without the need for user input.

FIGS. 5 and 6 further illustrate one embodiment of the attachmentportion 108. The attachment portion 108 provides alignment between thenatural limb of the amputee and the prosthesis 100 and may be configuredso as to decrease pressure peaks and shear forces. For example, theattachment portion 108 may be configured to attach to anotherprosthesis, to the stump of the amputee, or to another component. In oneembodiment, the attachment portion 108 comprises a socket connector. Thesocket connector may be configured to receive a 32 mm-thread component,a male pyramid type coupler, or other components. In other embodiments,the attachment portion 108 may also comprise, or be configured toreceive, a female pyramid adapter.

As depicted in FIGS. 5 and 6, the pivot assembly 114 is positioned tomimic a normal human ankle axis. FIG. 7 further illustrates a schematicdrawing indicating the correlation between an ankle pivot point on aprosthetic foot unit 204 with the natural human ankle joint of a foot.In particular, the prosthetic foot unit 204 comprises a pivot assembly214 that corresponds to an ankle joint 240 of a human foot 242. Forexample, in one embodiment of the invention, the pivot assembly 114 islocated near the mechanical ankle center of rotation of the prosthesis100.

FIG. 8 illustrates a graph depicting the possible range of ankle motionof an embodiment of the prosthesis 100 during one full stride on a levelsurface. As shown, the x-axis of the graph represents various pointsduring one full stride of a user (i.e., 0 to 100 percent). The y-axisrepresents the ankle angle (θ) of the prosthesis 100. During one fullstride, the ankle angle (θ) varies from approximately 20 degreesplantarflexion (i.e., neutral position angle +20 degrees) toapproximately 10 degrees dorsiflexion (i.e., neutral position angle −20degrees).

In embodiments as described above, no dampening is provided whenadjusting the angular range of motion. In another embodiment of theinvention, the prosthesis 100 is configured to provide dampening orpassive, soft resistance to changes in the angle between the lower limbmember 102 and the foot unit 104. An example of a system for controllingsuch dampening is disclosed in U.S. Pat. No. 6,443,993, which is herebyincorporated herein by reference and is to be considered as a part ofthis specification.

For example, when the user is in a standing position, the actuator 116may provide for increased resistance, or dampening, so as to providestability to the user. In one embodiment of the invention, dampening ofthe prosthesis 100 may be provided by hydraulic dampers. In otherembodiments of the invention, other components or devices that are knownin the art may be used to provide dampening for the prosthesis 100. Inaddition, in one embodiment of the invention, the dampers may bedynamically controlled, such as through an electronic control system,which is discussed in more detail below. In yet other embodiments, thedampers may be controlled through mechanical and/or fluid-typestructures.

It is also recognized that, although the above description has beendirected generally to prosthetic systems and devices, the descriptionmay also apply to an embodiment of the invention having an orthoticsystem or device. For example, in one embodiment of the invention, anorthotic system may comprise at least one actuator that activelycontrols the angle of an orthosis that is used with an injured ordebilitated ankle. In addition, the orthotic system may, in addition tothe electronic control of the orthotic system, provide for the user'scontrol or natural movement of the injured ankle or leg.

In addition, the above-described systems may be implemented inprosthetic or orthotic systems other than transtibial, orbelow-the-knee, systems. For example, in one embodiment of theinvention, the prosthetic or orthotic system may be used in atransfemoral, or above-the-knee, system, such as is disclosed in U.S.Provisional Application No. 60/569,512, filed May 7, 2004, and entitled“MAGNETORHEOLOGICALLY ACTUATED PROSTHETIC KNEE;” U.S. ProvisionalApplication No. 60/624,986, filed November 3, 2004, and entitled“MAGNETORHEOLOGICALLY ACTUATED PROSTHETIC KNEE;” and U.S. patentApplication Ser. No. 11/123,870, filed May 6, 2005, and entitled“MAGNETORHEOLOGICALLY ACTUATED PROSTHETIC KNEE;” each of which is herebyincorporated herein by reference in its entirety and is to be consideredas part of this specification. For example, the prosthetic or orthoticsystem may include both a prosthetic or orthotic ankle and/or aprosthetic or orthotic knee.

FIG. 9 illustrates a block diagram of one embodiment of a systemarchitecture of a control system 300 for an ankle-motion-controlledfoot. In one embodiment of the invention, the control system 300 isusable by the lower limb prosthesis 100 depicted in FIGS. 1-6. In otherembodiments of the invention the control system 300 is usable by anorthotic system or a rehabilitation system having anankle-motion-controlled foot, or other motion-controlled limb. In oneembodiment, the control system 300 is based on a distributed processingsystem wherein the different functions performed by the prosthetic ororthotic system, such as sensing, data processing, and actuation, areperformed or controlled by multiple processors that communicate witheach other. With reference to FIG. 9, the control system 300 includes asensor module 302, an ankle device 304 (such as, for example, theprosthesis 100 depicted in FIG. 1), a central processing unit (“CPU”)305, a memory 306, an interface module 308, a control drive module 310,an actuator 316 and a power module 318.

In one embodiment, the control system 300 depicted in FIG. 9 processesdata received from the sensing module 302 with the CPU 305. The CPU 305communicates with the control drive module 310 to control the operationof the actuator 316 so as to mimic natural ankle movement by the ankledevice 304. Furthermore, the control system 300 may predict how theankle device 304 may need to be adjusted in order to accommodatemovement by the user. The CPU 305 may also receive commands from a userand/or other device through the interface module 308. The power module318 provides power to the other components of the control system 300.Each of these components is described in more detail below.

In one embodiment, the sensor module 302 is used to measure variablesrelating to the ankle device 304, such as the position and/or themovement of the ankle device 304 throughout a gait cycle. In such anembodiment the sensor module 320 is advantageously located on the ankledevice 304. For example, the sensor module 302 may be located near amechanical ankle center of rotation of the ankle device 304, such as thepivot assembly 114 of the prosthesis 100 depicted in FIG. 2. In anotherembodiment, the sensor module 302 may be located on the user's naturallimb that is attached to, or associated with, the ankle device 304. Insuch an embodiment, the sensors are used to capture information relatingto the movement of the natural limb on the user's ankle-device side toadjust the ankle device 304.

In one embodiment, the sensor module 302 advantageously includes aprinted circuit board housing, multiple sensors, such as accelerometers,which each measures an acceleration of the ankle device 304 in adifferent axis. For example, the sensor module 302 may comprise threeaccelerometers that measure acceleration of the ankle device 304 inthree substantially, mutually perpendicular axes. Sensors of the typesuitable for the sensor module 302 are available from, for example,Dynastream Innovations, Inc. (Alberta, Canada).

In other embodiments, the sensor module 302 may include one or moreother types of sensors in combination with, or in place of,accelerometers. For example, the sensor module 302 may include agyroscope configured to measure the angular speed of body segmentsand/or the ankle device 304. In other embodiments, the sensor module 302includes a plantar pressure sensor configured to measure, for example,the vertical plantar pressure of a specific underfoot area. In yet otherembodiments, the sensor module 302 may include one or more of thefollowing: kinematic sensors, single-axis gyroscopes, single- ormulti-axis accelerometers, load sensors, flex sensors or myoelectricsensors that may be configured to capture data from the user's naturallimb. U.S. Pat. No. 5,955,667, U.S. Pat. No. 6,301,964, and U.S. Pat.No. 6,513,381, also illustrate examples of sensors that may be used withembodiments of the invention, which patents are herein incorporated byreference in their entireties and are to be considered as part of thisspecification.

Furthermore, the sensor module 302 may be used to capture informationrelating to, for example, one or more of the following: the position ofthe ankle device 304 with respect to the ground; the inclination angleof the ankle device 304; the direction of gravity with respect to theposition of the ankle device 304; information that relates to a strideof the user, such as when the ankle device 304 contacts the ground(e.g., “heel strike”), is in mid-stride, or leaves the ground (e.g.,“toe-off”), the distance from the ground of the prosthesis 100 at thepeak of the swing phase (i.e., the maximum height during the swingphase); the timing of the peak of the swing phase; and the like.

In yet other embodiments, the sensor module 302 is configured to detectgait patterns and/or events. For example, the sensor module 302 maydetermine whether the user is in a standing/stopped position, is walkingon level ground, is ascending and/or descending stairs or slopedsurfaces, or the like. In other embodiments, the sensor module 302 isconfigured to detect or measure the heel height of the ankle device 304and/or determine a static shank angle in order to detect when the useris in a sitting position.

As depicted in FIG. 9, in one embodiment of the invention, the sensormodule 302 is further configured to measure environmental or terrainvariables including one or more of the following: the characteristics ofthe ground surface, the angle of the ground surface, the air temperatureand wind resistance. In one embodiment, the measured temperature may beused to calibrate the gain and/or bias of other sensors.

In other embodiments, the sensor module 302 captures information aboutthe movement and/or position of a user's natural limb, such as a healthyleg. In such an embodiment, it may be preferable that when operating onan incline or a decline, the first step of the user be taken with thehealthy leg. Such would allow measurements taken from the naturalmovement of the healthy leg prior to adjusting the ankle device 304. Inone embodiment of the invention, the control system 300 detects the gaitof the user and adjusts the ankle device 304 accordingly while the ankledevice 304 is in a swing phase of the first step. In other embodimentsof the invention, there may be a latency period in which the controlsystem 300 requires one or two strides before being able to accuratelydetermine the gait of the user and to adjust the ankle device 304appropriately.

In one embodiment of the invention, the sensor module 302 has a defaultsampling rate of 100 hertz (Hz). In other embodiments, the sampling ratemay be higher or lower than 100 Hz or may be adjustable by a user, ormay be adjusted automatically by software or parameter settings. Inaddition, the sensor module 302 may provide for synchronization betweentypes of data being sensed or include time stamping. The sensors mayalso be configured so as to have an angular resolution of approximately0.5 degrees, allowing for fine adjustments of the ankle device 304.

In one embodiment, the sensor module 302 is configured to power downinto a “sleep” mode when sensing is not needed, such as for example,when the user is relaxing while in a sitting or reclining position. Insuch an embodiment, the sensor module 302 may awake from the sleep stateupon movement of the sensor module 302 or upon input from the user. Inone embodiment, the sensor module 302 consumes approximately 30milliamps (mA) when in an “active” mode and approximately 0.1 mA when ina “sleep”mode.

FIG. 9 illustrates the sensor module 302 communicating with the CPU 305.In one embodiment, the sensor module 302 advantageously providesmeasurement data to the CPU 305 and/or to other components of thecontrol system 300. In one embodiment, the sensor module 302 is coupledto a transmitter, such as, for example, a Bluetooth® transmitter, thattransmits the measurements to the CPU 305. In other embodiments, othertypes of transmitters or wireless technology may be used, such asinfrared, WiFi®, or radio frequency (RF) technology. In otherembodiments, wired technologies may be used to communicate with the CPU305.

In one embodiment, the sensor module 302 sends a data string to the CPU305 that comprises various types of information. For example, the datastring may comprise 160 bits and include the following information:[TS; AccX; AccY; AccZ; GyroX, GyroY, GyroZ, DegX, DegY, FS, M];

wherein TS=Timestamp; AccX=linear acceleration of foot along X axis;AccY=linear acceleration of foot along Y axis; AccZ=linear accelerationof foot along Z axis; GyroX=angular acceleration of foot along X axis;GyroY=angular acceleration of foot along Y axis; GyroZ=angularacceleration of foot along Z axis; DegX=foot inclination angle incoronal plane; DegY=foot inclination angle in sagittal plane; FS=logicstate of switches in the ankle device 304; and M=orientation of thesensors. In other embodiments of the invention, other lengths of datastrings comprising more or less information may be used.

The CPU 305 advantageously processes data received from other componentsof the control system 300. In one embodiment of the invention, the CPU305 processes information relating to the gait of the user, such asinformation received from the sensor module 302, determines locomotiontype (i.e., gait pattern), and/or sends commands to the control drivemodule 310. For example, the data captured by the sensor module 302 maybe used to generate a waveform that portrays information relating to thegait or movement of the user. Subsequent changes to the waveform may beidentified by the CPU 305 to predict future movement of the user and toadjust the ankle device 304 accordingly. In one embodiment of theinvention, the CPU 305 may detect gait patterns from as slow as 20 stepsper minute to as high as 125 steps per minute. In other embodiments ofthe invention, the CPU 305 may detect gait patterns that are slower than20 steps per minute or higher than 125 steps per minute.

In one embodiment of the invention, the CPU 305 processes data relatingto state transitions according to the following table (TABLE 1). Inparticular, TABLE 1 shows possible state transitions usable with thecontrol system 300. The first column of TABLE 1 lists possible initialstates of the ankle device 304, and the first row lists possible secondstates of the ankle device 304. The body of TABLE 1 identifies thesource of data used by the CPU 305 in controlling, or activelyadjusting, the actuator 316 and the ankle device 304 during thetransition from a first state to a second state; wherein “N” indicatesthat no additional data is needed for the state transition; “L”indicates that the CPU 305 uses transition logic to determine theadjustments to the ankle device 304 during the state transition; and “I”indicates the CPU receives data from an interface (e.g., interfacemodule 308, external user interface, electronic interface or the like).Transition logic usable with embodiments of the invention may bedeveloped by one with ordinary skill in the relevant art. Examples oftransition logic used in similar systems and methods to embodiments ofthe present invention are disclosed in U.S. Provisional Application No.60/572,996, entitled “CONTROL SYSTEM AND METHOD FOR A PROSTHETIC KNEE,”filed May 19,2004, and U.S. application Ser. No. 11/077,177, entitled“CONTROL SYSTEM AND METHOD FOR A PROSTHETIC KNEE,” filed March 9,2005,each of which is hereby incorporated herein by reference in itsentirety and is to be considered as a part of this specification. TABLE1 TRANSITIONS HEEL_(—) FROM STATE HEIGHT_(—) SENSOR_(—) STAIRS_(—)STAIRS_(—) TO STATE OFF CAL CAL NEUTRAL WALK UP DOWN RELAX PANTS OFF N II I N N N I I HEEL_HEIGHT_CAL L N N L N N N N N SENSOR_CAL L N N L N N NN N NEUTRAL I I I N L L L L I WALK I N N L N L L N N STAIRS_UP I N N L LN L N N STAIRS_DOWN I N N L L L N N N RELAX I N N L N N N N I PANTS I NN I N N N N N

In one embodiment, the above described states in TABLE 1 are predefinedstates of the ankle device 304. For example, the “OFF” state mayindicate that the functions of the ankle device 304 and the actuator 316are in an off or suspend mode. The “HEEL_HEIGHT_CAL” state relates tothe measuring of a heel height from a static sensor angle such as, forexample, when the ankle device 304 is not in motion. The “SENSOR_CAL”state relates to surface angle calibration when the user is walking on alevel surface. The “NEUTRAL” state relates to when the ankle device 304is locked in a substantially fixed position. The “WALK” state relates towhen the user is walking, such as on a level or sloped surface. “The“STAIRS_UP” and “STAIRS_DOWN” states relate to when the user is walking,respectively, up and down stairs. The “RELAX” state relates to when theuser is in a relaxed position. For example, in one embodiment, the“RELAX” state relates to when a user is in a sitting position with thelimb having the ankle device 304 crossed over the other limb. In such anembodiment, the control system 300 may cause the ankle device 304 tomove into a maximum plantarflexion position to mimic, for example, thenatural position and/or look of a healthy foot. The “PANTS” staterelates to when a user is putting on pants, trousers, shorts or thelike. In such a state, the control system 300 may, in one embodiment,cause the ankle device 304 to move into a maximum plantarflexionposition to facilitate putting the clothing on over the ankle device304.

In other embodiments of the invention, other states are usable with theankle device 304 in place of, or in combination with, the statesidentified in TABLE 1. For example, states may be defined thatcorrespond to lying down, cycling, climbing a ladder or the like.Furthermore, in controlling the state transitions, the CPU 305 and/orcontrol system 300 may process or derive data from sources other thanthose listed in TABLE 1.

In other embodiments, the CPU 305 may perform a variety of otherfunctions. For example, the CPU 305 may use information received fromthe sensor module 302 to detect stumbling by the user. The CPU 305 mayfunction as a manager of communication between the components of thecontrol system 300. For example, the CPU 305 may act as the masterdevice for a communication bus between multiple components of thecontrol system 300. As illustrated, in one embodiment, the CPU 305communicates with the power module 318. For example, the CPU 305 mayprovide power distribution and/or conversion to the other components ofthe control system 300 and may also monitor battery power or batterylife. In addition, the CPU 305 may function so as to temporarily suspendor decrease power to the control system 300 when a user is in a sittingor a standing position. Such control provides for energy conservationduring periods of decreased use. The CPU 305 may also process errorhandling, such as when communication fails between components, anunrecognized signal or waveform is received from the sensor module 302,or when the feedback from the control drive module 310 or the ankledevice 304 causes an error or appears corrupt.

In yet other embodiments of the invention, the CPU 305 uses or computesa security factor when analyzing information from the sensor module 302and/or sending commands to the control drive module 310. For example,the security factor may include a range of values, wherein a highervalue indicates a higher degree of certainty associated with adetermined locomotion type of the user, and a lower security factorindicates a lower degree of certainty as to the locomotion type of theuser. In one embodiment of the invention, adjustments are not made tothe ankle device 304 unless the locomotion type of the user isrecognized with a security factor above a predetermined threshold value.

In one embodiment, the CPU 305 includes modules that comprise logicembodied in hardware or firmware, or that comprise a collection ofsoftware instructions written in a programming language, such as, forexample C++. A software module may be compiled and linked into anexecutable program, installed in a dynamic link library, or may bewritten in an interpretive language such as BASIC. It will beappreciated that software modules may be callable from other modules orfrom themselves, and/or may be invoked in response to detected events orinterrupts. Software instructions may be embedded in firmware, such asan EPROM or EEPROM. It will be further appreciated that hardware modulesmay be comprised of connected logic units, such as gates and flip-flops,and/or may be comprised of programmable units, such as programmable gatearrays or processors.

FIG. 9 further depicts CPU 305 including a memory 306 for storinginstructions and/or data. For example, the memory 306 may store one ormore of the following types of data or instructions: an error log forthe other components of the control system 300; information regardinggait patterns or curves; information regarding past activity of the user(e.g., number of steps); control parameters and set points; informationregarding software debugging or upgrading; preprogrammed algorithms forbasic movements of the prosthetic or orthotic system; calibration valuesand parameters relating to the sensor module 302 or other components;instructions downloaded from an external device; combinations of thesame or the like.

The memory 306 may comprise any buffer, computing device, or systemcapable of storing computer instructions and/or data for access byanother computing device or a computer processor. In one embodiment, thememory 306 is a cache that is part of the CPU 305. In other embodimentsof the invention, the memory 306 is separate from the CPU 305. In otherembodiments of the invention, the memory 306 comprises random accessmemory (RAM) or may comprise other integrated and accessible memorydevices, such as, for example, read-only memory (ROM), programmable ROM(PROM), and electrically erasable programmable ROM (EEPROM). In anotherembodiment, the memory 306 comprises a removable memory, such as amemory card, a removable drive, or the like.

In one embodiment, the CPU 305 may also be configured to receive throughthe interface module 308 user- or activity-specific instructions from auser or from an external device. The CPU 305 may also receive updates toalready existing instructions. Furthermore, the CPU 305 may communicatewith a personal computer, a personal digital assistant, or the like soas to download or receive operating instructions. Activity-specificinstructions may include, for example, data relating to cycling,driving, ascending or descending a ladder, adjustments from walking insnow or sand, or the like.

In one embodiment, the interface module 308 comprises an interface thatthe user accesses so as to control or manage portions or functions ofthe prosthetic or orthotic system. In one embodiment, the interfacemodule 308 is a flexible keypad having multiple buttons and/or multiplelight emitting diodes (LEDs) usable to receive information from and/orconvey information to a user. For example, the LEDs may indicate thestatus of a battery or may convey a confirmation signal to a user. Theinterface module 308 may be advantageously located on the ankle device304. Furthermore, the interface module 308 may comprise a USB connectorusable for communication to an external computing device, such as apersonal computer.

In a further embodiment, the interface module 308 comprises an on/offswitch. In another embodiment, the interface module 308 may receiveinput regarding the user-controlled heel height or a forced relaxed modeof the prosthetic or orthotic system. In other embodiments, the user mayadjust the type of response desired of the prosthesis or enable/disableparticular functions of the ankle device 304. The input from the usermay be entered directly via the interface module 308, such as throughactuating a button, or user input may be received via a remote control.

The interface module 308 may comprise a touch screen, buttons, switches,a vibrator, an alarm, or other input-receiving or output structures ordevices that allow a user to send instructions to or receive informationfrom the control system 300. In another embodiment of the invention, theinterface module 308 comprises an additional structure, such as a plug,for charging a battery powering the control system 300, such as at homeor in a vehicle. In other embodiments of the invention, the interfacemodule 308 may also communicate directly or indirectly with componentsof the control system 300 other than the CPU 305.

The control drive module 310 is used to translate high-level plans orinstructions received from the CPU 305 into low-level control signals tobe sent to the actuator 316. In one embodiment, the control drive module310 comprises a printed circuit board that implements control algorithmsand tasks related to the management of the actuator 316. In addition,the control drive module 310 may be used to implement a hardwareabstraction layer that translates the decision processes of the CPU 305to the actual hardware definition of the actuator 316. In anotherembodiment of the invention, the control drive module 310 may be used toprovide feedback to the CPU 305 regarding the position or movement ofthe actuator 316 or ankle device 304. The control drive module 310 mayalso be used to adjust the actuator 316 to a new “neutral” setting upondetection by the CPU 305 that the user is traveling on an angledsurface.

In one embodiment of the invention, the control drive module 310 islocated within the ankle device 304. In other embodiments, the controldrive module 310 may be located on the outside of the ankle device 304,such as on a socket, or remote to the ankle device 304.

The actuator 316 provides for the controlled movement of the ankledevice 304. In one embodiment, the actuator 316 functions similarly tothe actuator 116 described with respect to FIGS. 1-6, which actuator 116controls the ankle motion of the prosthesis 100. In other embodiments ofthe invention, the actuator 316 may be configured to control the motionof an orthotic device, such as a brace or other type of supportstructure.

The ankle device 304 comprises any structural device that is used tomimic the motion of a joint, such as an ankle, and that is controlled,at least in part, by the actuator 316. In particular, the ankle device304 may comprise a prosthetic device or an orthotic device.

The power module 318 includes one or more sources and/or connectorsusable to power the control system 300. In one embodiment, the powermodule 318 is advantageously portable, and may include, for example, arechargeable battery, as discussed previously. As illustrated in FIG. 9,the power module 318 communicates with the control drive module 310 andthe CPU 305. In other embodiments, the power module 318 communicateswith other control system 300 components instead of, or in combinationwith, the control drive module 310 and the CPU 305. For example, in oneembodiment, the power module 318 communicates directly with the sensormodule 302. Furthermore, the power module 318 may communicate with theinterface module 308 such that a user is capable of directly controllingthe power supplied to one or more components of the control system 300.

The components of the control system 300 may communicate with each otherthrough various communication links. FIG. 9 depicts two types of links:primary communication links, which are depicted as solid lines betweenthe components, and secondary communication links, which are depicted asdashed lines. In one embodiment, primary communication links operate onan established protocol. For example, the primary communication linksmay run between physical components of the control system 300. Secondarycommunication links, on the other hand, may operate on a differentprotocol or level than the primary communication links. For example, ifa conflict exists between a primary communication link and a secondarycommunication link, the data from the primary communication link willoverride the data from the secondary communication link. The secondarycommunication links are shown in FIG. 9 as being communication channelsbetween the control system 300 and the environment. In other embodimentsof the invention, the modules may communicate with each other and/or theenvironment through other types of communication links or methods. Forexample, all communication links may operate with the same protocol oron the same level of hierarchy.

It is also contemplated that the components of the control system 300may be integrated in different forms. For example, the components can beseparated into several subcomponents or can be separated into moredevices that reside at different locations and that communicate witheach other, such as through a wired or wireless network. For example, inone embodiment, the modules may communicate through RS232 or serialperipheral interface (SPI) channels. Multiple components may also becombined into a single component. It is also contemplated that thecomponents described herein may be integrated into a fewer number ofmodules. One module may also be separated into multiple modules.

Although disclosed with reference to particular embodiments, the controlsystem 300 may include more or fewer components than described above.For example, the control system 300 may further include an actuatorpotentiometer usable to control, or fine- tune, the position of theactuator 316. The user may also use the actuator potentiometer to adjustthe heel height of the ankle device 304. In one embodiment, the actuatorpotentiometer communicates with the CPU 305. In other embodiments, thecontrol system 300 may include a vibrator, a DC jack, fuses,combinations of the same, or the like.

Examples of similar or other control systems and other relatedstructures and methods are disclosed in U.S. patent application Ser. No.10/463,495, filed Jun. 17, 2003, entitled “ACTUATED LEG PROSTHESIS FORABOVE-KNEE AMPUTEES,” now published as U.S. Publication No.2004/0111163;U.S. patent application Ser. No. 10/600,725, filed Jun. 20,2003,entitled “CONTROL SYSTEM AND METHOD FOR CONTROLLING AN ACTUATEDPROSTHESIS,” now published as U.S. Publication No. 2004/0049290; U.S.patent application Ser. No. 10/627,503,filed Jul. 25, 2003, entitled“POSITIONING OF LOWER EXTREMITIES ARTIFICIAL PROPRIOCEPTORS,” nowpublished as U.S. Publication No. 2004/0088057, U.S. patent applicationSer. No. 10/721, 764, filed Nov. 25, 2003, entitled “ACTUATED PROSTHESISFOR AMPUTEES,” now published as U.S. Publication No. 2004/0181289; andU.S. patent application Ser. No. 10/715,989, ,” filed Nov. 18, 2003,entitled “INSTRUMENTED PROSTHETIC FOOT,” now published as U.S.Publication No. 2005/0107889; each which is herein incorporated byreference in its entirety and is to be considered as part of thisspecification. In addition, other types of control systems that may beused in embodiments of the present invention are disclosed in U.S.Provisional Application No. 60/551,717, entitled “CONTROL SYSTEM FORPROSTHETIC KNEE,” filed Mar. 10, 2004; U.S. Provisional Application No.60/569,511, entitled “CONTROL SYSTEM AND METHOD FOR A PROSTHETIC KNEE,”filed May 7, 2004;and U.S. Provisional Application No. 60/572,996,entitled “CONTROL SYSTEM AND METHOD FOR A PROSTHETIC KNEE,” filed May19, 2004, which are herein incorporated by reference in their entiretiesto be considered as part as this specification.

FIG. 10 is a table that depicts possible control signals that may beinvolved in adjusting the ankle angle of a prosthetic or orthotic devicewhen a user is transitioning between different states, or types oflocomotion, according to one embodiment of the invention. In particular,the states listed in a column 402 identify a first state of the user,and the states listed in a row 404 identify a second state of the user,or the state to which the user is transitioning. The remainder of thetable identifies possible actions that may be taken by the prosthetic ororthotic device with respect to the ankle angle. “User set point” is theneutral, or default, value that may be set during shoe heel heightadjustment. The angles specified are examples of changes to the ankleangle of the prosthetic or orthotic device. For example, when a user istransitioning from a “stance” state to an “ascending stairs” state, theankle angle may be adjusted to the angle of the stairs, such as forexample, −10 degrees (or 10 degrees dorsiflexion). Ankle angles given inthe “Incline (up)” and “Decline” columns reflect threshold levels ofankle angle adjustment depending on the angle of the incline.

The following table (TABLE 2) illustrates possible ankle motionstrategies for one embodiment of the invention. The first column ofTABLE 2 lists different types of locomotion types or gait patterns thatmay be frequently detected. The second column of TABLE 2 identifiesexamples of ankle angle adjustment of the prosthetic or orthotic deviceduring the swing phase of each of the identified locomotion types. TABLE2 Locomotion Type/Gait Pattern Ankle Motion During Swing Phase of AnkleDevice Level Ground Toe clearance during swing Walking Ascending StairsAnkle adjusts to dorsiflexion (e.g., 7.5°) Descending Stairs Ankleadjusts to dorsiflexion (e.g., 5°) Incline (up) Ankle adjust todorsiflexion: a) Two incline angle threshold levels (x°, y°) b) Stepwise(2 steps) angle adjustment (z°, w°) Example: If incline angle > x°,ankle will adjust to −z°; if incline angle > y°, ankle will adjust to−w°, wherein x = 2.5° and y = 5°. Decline Ankle adjusts toplantarflexion: a) Two decline angle threshold levels (x°, y°) b)Stepwise (2 steps) angle adjustment (z°, w°) Example: If decline angle >x°, ankle will adjust to z°; if decline angle > y°, ankle will adjust tow°, wherein x = 2.5° and y = 5°. Sitting/Relaxed Set Heel Height AdjustHeel Stepless heel height adjustment up to 20° Height plantarflexion

FIG. 11 depicts a graph that illustrates the interaction andrelationship between the control of a prosthetic or orthotic leg and themeasurements taken from a healthy, sound leg. In particular, FIG. 11depicts the movement of a prosthetic or orthotic leg and a healthy legduring one full stride of a user. For example, during approximately thefirst 60% of the stride, the graph shows the prosthetic or orthotic legas being in a “stance” position or being planted on a surface, such asthe ground. In one embodiment, during the beginning portion of thestance phase the ankle angle of the prosthetic or orthotic leg maydecrease (dorsiflexion). Toward the end of the stance phase the ankleangle of the prosthetic or orthotic leg may then increase(plantarflexion) to facilitate natural stride movements. In otherembodiments of the invention, the ankle angle of the prosthetic ororthotic leg is not actively adjusted during the stance phase. During aportion of this same period, up to approximately point 40%, the healthyleg may be in a swinging position, wherein the healthy leg is not incontact with the ground. Between the points of approximately 40% and60%, both legs are in contact with the ground.

From approximately point 60% to 100% (the end of the stride), theprosthetic or orthotic leg is in a swinging position, and the healthyleg is in contact with the ground. The graph in FIG. 11 shows that theankle angle of the prosthetic or orthotic leg is adjusted during theswing phase. This angle adjustment may be based on previous measurementsof the healthy leg during the swing phase of the healthy leg. In oneembodiment, during the beginning portion of the swing phase of theprosthetic or orthotic leg, the ankle angle of the prosthetic ororthotic leg may decrease. This allows, for example, a toe portion ofthe prosthetic or orthotic leg to clear stairs. Toward the latterportion of the swing phase of the prosthetic or orthotic leg, the ankleangle of the prosthetic or orthotic leg may then increase beforecontacting the ground. In other embodiments, the angle adjustment isbased on readings taken by sensors on the prosthetic side.

It is to be understood that FIG. 11 is illustrative of the functioningof one embodiment of the invention under certain conditions. Otherembodiments or circumstances may require a longer or shorter stance orswing phase and require other adjustments to the angle of the ankleportion of the prosthetic leg.

FIGS. 12A-12C illustrate another embodiment of a lower limb prosthesis100′ configured to be attached to a human limb. The lower limbprosthesis 100′ is similar to the lower limb prosthesis 100 illustratedin FIG. 2, except as noted below. Thus, the reference numerals used todesignate the various components of the lower limb prosthesis 100′ areidentical to those used for identifying the corresponding components ofthe lower limb prosthesis 100 in FIG. 2, except that a “′” has beenadded to the reference numerals.

The lower limb prosthesis 100′ comprises a first portion 102′ coupled toa second portion 104′, wherein the portions 102′, 104′ are moveablerelative to each other to mimic a natural human joint. In theillustrated embodiment, the first portion is a lower limb member 102′and the second portion is a prosthetic foot unit 104′ coupled to thelower limb member 102′ to mimic a natural human ankle joint. The footunit 104′ includes a heel portion 104 a′ at a rear end of the foot unit104′ and a toe portion 104 b′ at a front end of the foot unit 104′. Inone embodiment, the heel and toe portions 104 a′, 104 b′ can be unitary.In another embodiment, the heel and toe portions 104 a′, 104 b′ can beseparate components fastened to each other via, for example, bolts,screws, adhesives and the like. In the illustrated embodiment, theprosthetic foot unit 104′ is an LP VARI-FLEX® prosthetic footcommercially available from Ossur. However, the foot unit 104′ can haveother configurations or designs. In another embodiment (not shown), thefirst and second portions can be an upper leg member and a lower legmember, respectively, which are coupled to mimic a natural human kneejoint.

As shown in FIG. 12A, the lower limb prosthesis 100′ may also comprise aframe 106′ extending between the foot unit 104′ and the lower limbmember 102′. As shown in FIGS. 12A and 12B, an attachment portion 108′of the lower limb member 102′ facilitates the coupling of the lower limbmember 102′ to another member, such as, for example, the pylon 110depicted in FIGS. 1-4.. In the illustrated embodiment, the attachmentportion 108′ is a pyramid. Additionally, the lower limb member 102′, orsupport member, couples to the foot unit 104′ at its lower end via apivot assembly 114′, which is attached to the prosthetic foot unit 104′.In the illustrated embodiment, the pivot assembly 114′ is attached atabout the rear ⅓ of the foot unit 104′. However, the pivot assembly 114′can be attached at other locations on the foot unit 104′. Preferably,the pivot assembly 114′ mimics a natural human ankle joint.Additionally, a cover 106 b′ is disposed about an actuator 500 of thelower limb prosthesis 100′ to substantially protect the actuator 500 andinhibit the intrusion of foreign matter. In certain embodiments, thelower limb prosthesis 100′ may also include a control wire, such as thecontrol wire 112 depicted in FIGS. 1-4, to provide power to and/orcommunicates control signals to the prosthesis 100′.

With continued reference to FIGS. 12A-12C, the actuator 500 provides theprosthesis 100′ with the necessary energy to execute angulardisplacements synchronized with an amputee's locomotion. The actuator500 couples the first and second portions 102′, 104′ of the prosthesis100′ together, which in the illustrated embodiment correspond to thelower limb member 102′ and the prosthetic foot unit 104′. As discussedfurther below, the actuator is configured to adjust an angle between thelower limb member 102′ and the foot unit 104′. The actuator 500 couplesto the foot unit 104′ and the lower limb member 102′ at first and secondattachment points 118′, 120′, respectively. In one embodiment, theprosthesis can include control circuitry to control the operation of theactuator 500, such as, for example, the control circuitry 122 depictedin FIGS. 2 and 3.

FIGS. 13-18 illustrate one embodiment of an actuator 500 that may beused with the lower limb prosthesis 100′ discussed above. The actuator500 preferably comprises a stator or top unit 510 having an attachmentend 512 and a bottom end 514. In the illustrated embodiment, theattachment end 512 is a C-shaped clamp (see FIG. 15) having a firstopening 512 a and a second opening 512 b aligned along a first axis X1that extends generally perpendicular to a longitudinal axis Y of theactuator 500. However, the attachment end 512 can have other suitableconfigurations. The openings 512 a, 512 b are preferably sized toreceive a fastener therethrough, such as a bolt, screw, or pin (notshown), to allow the top unit 510 to be fastened to, for example, theupper end of the lower limb member 102′ at the second attachment point120′.

The bottom end 514 of the top unit 510 preferably has a circumferentialwall 514 a and a bottom surface 516. In the illustrated embodiment, asshown in FIG. 17, the bottom surface 516 curves from the circumferentialwall 514 a toward a center of the bottom surface 516. The bottom surface516 preferably includes a recess portion 518 located generally at thecenter of the bottom surface 516. The recess portion 518 on the bottomsurface 516 of the top unit 510 is preferably sized to receive a ballbearing 522 therein, as further discussed below.

As illustrated in FIG. 17, the circumferential wall 514 a includes aprotrusion 520 that extends outward from the wall 514 a. In oneembodiment, the protrusion 520 extends substantially along the entirecircumference of the wall 514 a. In another embodiment, the protrusion520 can be a plurality of protrusions positioned at discrete locationsabout the circumference of the wall 514 a.

The actuator 500 also comprises a first elongate member or rotor 530with a body extending from a top end 530 a to a bottom end 530 b along alength 532, and having a diameter 534. In one embodiment, the length 532is between about 25 mm and about 70 mm. In one embodiment, the diameter534 is between about 12 mm and about 40 mm. More preferably, thediameter 534 is about 17 mm. The rotor 530 has a circumferential flange536 at the top end 530 a, the flange 536 having a diameter greater thanthe diameter 534 of the body. The top end 530 a has an outer surface 537that curves generally upward from the circumferential flange toward acenter 537 a of the surface 537. The surface 537 defines a recessedportion 538 generally disposed at the center 537 a thereof. The recessedportion 538 is preferably contoured to receive the ball bearing 522therein, such that the ball bearing 522 couples the top unit 510 to therotor 530. In one preferred embodiment, the top unit 510 and the rotor530 couple to each other solely via the ball bearing 522. In theillustrated embodiment, the ball bearing 522 is a single ball bearing.However, other suitable bearings can be used. In one embodiment (notshown) a thrust bearing is disposed between the top unit 510 and therotor 530. As shown in FIG. 17, the rotor 530 is preferably an elongatenut defining a hollow central portion 539, which defines a wall 539 awith threads 540 disposed along at least a portion the length of thewall 539 a.

As discussed above, the ball bearing 522 preferably couples the top unit510 to the first elongate member 530. Preferably, the curvature of thesurface 537 of the rotor 530 and the curvature of the bottom surface 516of the top unit 510 define a gap 541 therebetween. The gap 541 extendspreferably circumferentially about the center 537 a of the surface 537.In a preferred embodiment, at least one magnet 542 is disposed in thegap 541 and attached to the surface 537 via, for example, an adhesive.In the embodiment illustrated in FIG. 18, a plurality of magnets 542 aredisposed about the center 537 a of the surface 537. In anotherembodiment, an annular magnet (not shown) can be disposed on the surface537, with the annulus of the magnet aligned with the center 537 a. Themagnets 542 are preferably configured to exert a magnetic force on thetop unit 510 and the rotor 530, so that the force draws the top unit 510and the rotor 530 toward each other.

As best seen in FIGS. 17 and 18, the actuator 500 also includes aretainer 550 having a height 551 and a wall 552 defining an innerdiameter 554. The retainer 550 includes a flange 556 having an innerportion 556 a extending radially inward from the wall 552 and an outerportion 556 b extending radially outward from the wall 522, wherein theinner and outer portions 556 a, 556 b are preferably disposed at abottom end of the wall 552. Though the illustrated embodiment shows theflange 556 as being continuous around the circumference of the retainer550, one of ordinary skill in the art will recognize that the flange 556can instead be a plurality of flange members disposed at discretelocations about the circumference of the retainer 556. The innerdiameter 554 of the retainer 550 is sized to receive the rotor 530 andthe top unit 510 therein.

In the illustrated embodiment, the inner diameter 554 of the retainer550 is preferably at least slightly greater than the diameter of theflange 536 of the rotor 530, so that the flange 536 of the rotor 530does not engage the wall 552 of the retainer 550. Similarly, the innerdiameter 554 of the retainer 550 is preferably at least slightly greaterthan the diameter of at least a portion of the circumferential wall 514a of the top unit 510. The protrusions 520 on the circumferential wall514 a of the top unit 510 preferably engage a portion of the wall 552 ofthe retainer 550, such that the top unit 510 and the retainer 550 arecoupled to each other.

Preferably, rotor 530 rotates about, and translates along, thelongitudinal axis Y, as further discussed below. In one embodiment, therotor 530 remains coupled to the top unit 510 via the ball bearing 522,but selectively moves in and out of contact with the retainer 550 viathe inner flange 556 a, as further described below. In anotherembodiment, the rotor 530 moves between contact with the top unit 510,via the ball bearing 522, and contact with the retainer 550 via theinner flange 556 a.

As best shown in FIGS. 17 and 18, a first magnet 560 a and a secondmagnet 560 b are disposed about a portion of the rotor 530. The firstand second magnets 560 a, 560 b preferably have a height 562 a, 562 band an inner diameter 564 a, 564 b larger than the diameter 534 of therotor 530, so that the magnets 560 a, 560 b fit about the rotor 530. Inone embodiment, the inner diameters 564 a, 564 b of the first and secondmagnets 560 a, 560 bare between about 12 mm and about 40 mm, and morepreferably about 17 mm. In one embodiment, the magnets 560 a, 560 b aremagnetized rings with 24 poles. Additionally, as shown in FIG. 17-18, aspacer 568 is disposed between the first and second magnets 560 a, 560b. Preferably, the spacer 568 also has a diameter greater than thediameter 534 of the rotor 530, so that the spacer 568 fits about therotor 530. Though the illustrated embodiment depicts two magnets 560 a,560 b and one spacer 568, one of ordinary skill in the art willrecognize that any number of magnets and spacers can be used.

The actuator 500 also comprises a sleeve 570 with a cylindrical body 571having a length 572 and a diameter 574 such that the sleeve 570 fitsabout the rotor 530. In one embodiment, the length 572 is between about10 mm and about 70 mm, and more preferably about 20 mm. The diameter 574is preferably between about 12 mm and about 40 mm, and more preferablyabout 17 mm. Preferably, as shown in FIG. 17, the sleeve 570 has aninner diameter greater than the diameter 534 of the first elongatemember 530, and has an outer diameter that is smaller than the innerdiameter of the first and second magnets 560 a, 560 b and the spacer568. Accordingly, the first and second magnets 560 a, 560 b and thespacer 568 fit about the sleeve 570, which in turn fits about the rotor530. In a preferred embodiment, the rotor 530, sleeve 570, magnets 560a, 560 b are disposed substantially adjacent each other.

As best illustrated in FIGS. 17 and 18, the sleeve 570 also has a lip576 that extends circumferentially about the sleeve 570. In a preferredembodiment, the lip 576 extends continuously around the sleeve 570 at aradial distance away from a surface of the sleeve 570 substantiallyequal to a thickness of at least one of the first and second magnets 560a, 560 b. The lip 576 is preferably positioned a distance away from atop end of the sleeve 570 so as to support the first and second magnets560 a, 560 b and the spacer 568 about the sleeve 570 so that the firstand second magnets 560 a, 560 b and the spacer 568 do not extend pastthe top end of the sleeve 570.

The actuator 500 also comprises a motor 580. In the illustratedembodiment, the motor 580 has a height 582 and an inner surface 586 withan inner diameter 584, such that the motor 580 can be disposed about therotor 530. In one embodiment, the motor has a length of between about 10mm and about 60 mm, and more preferably about 25 mm. the inner diameter584 of the motor 580 is preferably between about 15 mm and about 50 mm.In a preferred embodiment, the diameter 584 of the motor 580 is about 22mm. As illustrated in FIG. 17, the motor 580 extends about the rotor530, such that the sleeve 570, the first and second magnets 560 a, 560 band the spacer 568 are disposed between the rotor 530 and the innerdiameter 584 of the motor 580. The motor 580 preferably compriseswindings configured to rotate the rotor 530 via the magnets 560 a, 560b. In the illustrated embodiment, the motor 580 is a stepper motor.However, other suitable motor types can be used. For example, the motor580 can be a DC motor, a piezo-electric motor, a DC brushless motor, anda servo motor.

As best shown in FIG. 18, the actuator also comprises an o-ring 590 anda roller bearing 600 disposed between the motor 580 and a cover portion610 having a protruding portion 612. The cover 610 preferably houses themotor 580 therein when the actuator 500 is fully assembled. A bellows620 is preferably disposed adjacent a bottom end of the cover 610. Thebellows 620 advantageously inhibits the entry of foreign particles, suchas dust and water, into contact with the motor 580 and a second elongatemember 630 of the actuator 500.

The second elongate member 630 extends along a length 632 and has adiameter 634. In the illustrated embodiment, the second elongate member630 is a screw with threads 636 along a portion of the length 632. Inthe illustrated embodiment, the screw 630 has an attachment portion 638at a bottom end thereof with an opening 638 a that extends therethroughalong an axis X2 generally orthogonal to the longitudinal axis Y of theactuator 500. The opening 638 a is preferably sized to receive afastener therethrough, such as a bolt, a screw or a pin. Accordingly,the attachment portion 638 can be fastened to, for example, theprosthetic foot unit 104′ at the first attachment point 118 ′.

In one preferred embodiment, the threads 636 of the screw 630 areadapted to threadingly engage the threads 540 on the nut 530.Preferably, the threads 636, 540 to the screw 630 and the nut 530,respectively, are designed to be on the boundary of a self-lockingcoupling. In one preferred embodiment, the threads 636, 540 of the nut530 and the screw 630, respectively are trapezoidal threads. Forexample, the threads 636, 540 can be ACME centralized threads with aworking diameter of about 14 mm, a pitch of about 2 mm, and about twoleads. However, any suitable thread type can be used. In one embodiment,the threads 636, 540 are made of Aluminum Bronze and Stainless Steel.However, other suitable metals and alloys can be used. In one preferredembodiment, the threads 540 in the nut 530 are cut, while the threads636 in the screw 630 and ground and coated with a coating, such as apermanent oil coating. Advantageously, the thread lengths in the nut 530are configured to provide minimum friction during operation of theactuator 500, while delivering optimum support and strength to theactuator 500. However, one of ordinary skill in the art will recognizethat the threads 540, 636 of the nut 530 and the screw 630 can haveother configurations and be made of other materials to provide a desiredperformance characteristic. For example, the material and coating of thethreads, as well as the pitch, working diameter, and number of leads canbe varied to provide a different interface friction between the threads636, 540. In one embodiment, the pitch and configuration of the threads636, 530 can be chosen so that a load applied (e.g., along thelongitudinal axis Y) to the screw 630 and/or nut 530 assembly will notinitiate a self-generated movement of the actuator 500. That is, thepitch and configuration of the threads 636, 530 generate a frictionforce therebetween that is large enough to inhibit the relative rotationof the nut 530 and the screw 630. In another embodiment, the pitch andconfiguration of the threads 636, 530 can be chosen so that a loadapplied to the screw 630 and/or nut 530 along the longitudinal axis Ywill initiate a self-generated movement of the actuator 500.

As shown in FIG. 17, the screw 630 preferably has a hollow portion 640extending along a portion of the length 632. Advantageously, the hollowportion 640 reduces the weight of the screw 630, thereby reducing theweight of the actuator 500 as a whole. As shown in FIG. 18, an adoptionring 650 is disposed about the screw 630, wherein the ring 650 coupleswith the bottom end of the bellows 620.

Advantageously, the actuator 500 has a compact assembly. As discussedabove, the motor 580 is disposed about the rotor 530, which is disposedabout the elongate member or screw 630. Accordingly, the actuator 500takes up less space and can have a lower height than other designs. Inone preferred embodiment, the actuator 500 has a height of between about40 mm to about 70 mm in a collapsed configuration, and a height ofbetween about 65 mm to about 130 mm in a fully extended configuration.Additionally, the hollow portion 640 of the screw 630 advantageouslyreduces the weight of the actuator 500.

In operation, the actuator 500 advantageously minimizes friction betweenthe stator or top unit 510 and the rotor or nut 530. The ball bearing522 disposed between the top unit 510 and the nut 530 inhibits thegeneration of a friction force between the top unit 510 and the nut 530,thereby allowing the nut 530 to rotate generally freely relative to thetop 510. Additionally, the magnets 542 draw the nut 530 toward the topunit 510, as discussed above. Such a magnetic force lifts the nut 530from engagement with the inner flange 556 a of the retainer 550, therebyinhibiting the generation of friction between the retainer 550 and thenut 530, as further discussed below. In a preferred embodiment, themagnetic force is strong enough to lift the rotor 530 from engagementwith the inner flange 556 a of the retainer in one desired phase of agait cycle. In another embodiment, the magnetic force of the magnets 542is strong enough to lift the rotor 530 from engagement with the innerflange 556 a of the retainer 550 in more than one desired phase of agait cycle.

The actuator 500 can also advantageously be selectively locked during adesired phase of a gait cycle. As illustrated in FIG. 17, the flange 536of the rotor or nut 530 can engage the inner flange 556 a of theretainer 550, generating a friction force between the rotor 530 and theretainer 550 to inhibit the rotation of the rotor 530. Thus, thefriction force that is generated is effectively a locking force thatlocks the actuator 500. In one preferred embodiment, the flanges 536,556 a engage when the actuator 500 is in tension. Additionally, asdiscussed above, the interaction of the threads 636, 540 of the screw630 and the nut 530 can also generate a friction force to inhibit therotation of the screw 630 and the nut 530 relative to each other. Thus,the interaction of the threads 636, 540 also generates a locking forcethat contributes to the locking of the actuator 500.

The operation of the actuator 500 during the operation of the lower limbprosthesis 100′ by a user will now be described. FIG. 19 illustrates aflow chart showing the different phases of a gait cycle 670 of the lowerlimb prosthesis 100′ illustrated in FIGS. 12A-12C. In a first phase 672of the gait cycle 670, during heel strike of the foot unit 104′, theactuator 500 is initially in a state of compression, wherein the flange536 on the rotor 530 is displaced relative to the inner flange 556 a onthe retainer 550.

The state of compression in the first phase arises from the operatingrelationship between the lower limb member 102′ and the prosthetic footunit 104′. During heel strike, a load is applied on the heel portion 104a′ of the foot unit 104′ (e.g., due to the weight or locomotion force ofthe user). Said load applies an upward force on the heel portion 104 a′of the foot unit 104′, causing the toe portion 104 b′ to move away fromthe lower limb member 102′ by rotating about the main pivot axis of thepivot assembly 114′, which in turn applies a compression force on thesecond elongate member 630 via the first attachment point 118′. Thecompression force is transferred from the second elongate member 630onto the rotor 530, so that the flange 536 of the rotor 530 moves awayfrom the inner flange 556 a of the retainer 550.

In one preferred embodiment, the actuator 500 is not actuated during thefirst phase 672. However, to inhibit the rotation of the rotor 530relative to the second elongate member 630 during the first phase 672due to the applied load, the pitch of the threads 540, 636 between therotor 530 and the second elongated member 630 advantageously generate aninterface friction force between the threads 540, 636.

The lower limb prosthesis 100′ transitions into a second phase 674 wherethe foot unit 104′ is in a stance phase. During said transition, theactuator 500 transitions from a state of compression to a state oftension, so that a friction force is generated between the flange 536 ofthe rotor 530 and the inner flange 556 a of the retainer 550, asdiscussed above.

The state of tension in the stance phase is generated by the movement ofthe lower limb member 102′ relative to the prosthetic foot member 104′as the prosthesis 100′ transitions into the second phase 674. As theprosthesis 100′ moves through the second phase 674, the locomotion ofthe user (e.g., due to forward movement) applies a load on the lowerlimb member 102′, urging the lower limb member 102′ toward the toeportion 104 b′ of the prosthetic foot unit 104′, thus placing a load onthe toe portion 104 b′. Said load causes a rear portion of the foot unit104′ to move downward, away from the lower limb member 102′, which inturn applies a tension force on the second elongate member 630 via thefirst attachment point 118′. The tension force is transferred from thesecond elongate member 630 onto the rotor 530, so that the flange 536 ofthe rotor 530 moves toward, and into engagement with, the inner flange556 a of the retainer 550. As discussed above, said engagement betweenthe flange 536 of the rotor 530 and the inner flange 556 a of theretainer 550 generates a friction force to inhibit the rotation of therotor 530. In one preferred embodiment, the friction force is highenough to act as a brake to prevent the rotation of the rotor 530.Furthermore, in one preferred embodiment, the actuator 500 is notactuated during the second phase 674.

In a third phase 676, the foot unit 104′ transitions from a stance phaseto a toe-off phase. In toe-off, the toe portion 104 b′ continues to beunder load, as in the second phase. Accordingly, the actuator remainssubstantially in a state of tension, so that the rotor 530 is inhibitedfrom rotating, as discussed above. In one embodiment, the load on thetoe portion 104 b′ is greater in the third phase than in the secondphase of the gait cycle. In one preferred embodiment, the actuator 500is not actuated during the third phase 676.

In a fourth phase 678, the prosthetic foot unit 104′ is in a swing phasebetween toe-off and heel-strike, wherein the foot 104′ is not in contactwith a support surface. In the fourth phase 678, the actuator 500 is ina compression position. As discussed above, while in compression theflange 536 on the rotor 530 is separated from the inner flange 556 a ofthe retainer 550, thereby allowing the rotor 530 to rotate generallyfreely relative to the retainer 550.

The state of compression during the swing phase arises from theoperating relationship between the lower limb member 102′ and theprosthetic foot unit 104′. During the swing phase, a load is applied tothe prosthetic foot unit 104′ due to the configuration of the foot unit104′ (e.g., the weight of the foot unit 104′), which pulls the toeportion 104 b′ downward, away from the lower limb member 102′. Thedownward force on the toe portion 104 b′ in turn applies a compressionforce on the second elongate member 630 via the first attachment point118′. The compression force is transferred from the second elongatemember 630 onto the rotor 530, so that the flange 536 of the rotor 530moves away from the inner flange 556 a of the retainer 550. The rotor530 is thus able to rotate generally freely relative to the retainer550. In one embodiment, the movement of the flange 536 of the rotor 530away from the inner flange 556 a of the retainer 550 is facilitated bythe magnets 542, which draw the rotor 530 toward the top unit or stator510 and away from the retainer 550, thus inhibiting the generation offriction during the swing phase.

In one preferred embodiment, the actuator 500 is actuated during theswing phase to adjust the angle between the lower limb member 102′ andthe prosthetic foot 104′. Advantageously, the ball bearing 522 disposedbetween the stator 510 and the rotor 530 also inhibit the generation offriction between the rotor 530 and the retainer 550. Therefore, theactuator 500 is actuated while under a light load, which advantageouslyreduces the wear and tear on the actuator 500, providing for an extendedoperating life.

As discussed above, in one embodiment the actuator 500 inhibits therotation of the rotor 530 relative to the second elongate member 630when in a state of tension. However, one of ordinary skill in the artwill recognize that in another embodiment the actuator 500 can beoperated to inhibit the rotation of the rotor 530 relative to the secondelongate member 630 while in compression. Moreover, in anotherembodiment the actuator 500 can also be arranged so as to allow for therotation of the rotor 530 relative to the second elongate member 630when in a tension position. For example, in one embodiment the magnets542 can generate a magnetic force sufficient to draw the rotor 530 awayfrom the inner flange 556 a of the retainer 550 while the actuator 500is in a state of tension. Additionally, as discussed above, the actuator500 is actuated during the swing phase 678 of a gait cycle. However, oneof ordinary skill in the art will recognize that the actuator 500 can beactuated during more than one phase of a gait cycle.

Though the operation of the actuator 500 is discussed above in relationto a lower limb prosthesis 100′, one of ordinary skill in the art willrecognize that the actuator 500 can also be used with an orthotic deviceto adjust the angle of a first portion and a second portion of theorthotic device. Additionally, the actuator 500, as described in theembodiments above, can advantageously be used to selectively lock theorthotic device during a desired phase of locomotion, as well as tominimize friction between the rotor 530 and the retainer 550 during theactuation of the actuator 500 to facilitate the operation of theorthotic device.

In certain embodiments of the invention, a lower limb prosthesis ororthosis includes at least one sensing device coupled thereto and thatis substantially isolated from negative external effects or loads. Forexample, in certain embodiments, the sensing device is capable ofmeasuring angular movement of a prosthetic foot in a single directionwhile disregarding or filtering out movement and/or loads of theprosthetic foot in other directions.

For example, FIG. 20 illustrates a disassembled view of a lower limbprosthesis 700 having an ankle-motion-controlled foot unit. For ease ofreference and depiction, certain components, such as certain bolts,washers, bearing plugs and the like, are not shown and described withreference to the illustrated prosthesis 700. A skilled artisan wouldrecognize however, from FIG. 20 and the disclosure herein whichcomponents, or equivalents thereof, may be used with the depictedcomponents of the illustrated prosthesis 700.

In certain embodiments, the prosthesis 700 includes at least one sensorassembly that advantageously detects rotation of the foot unit about asingle axis and substantially neglects axial and radial movement of thefoot unit with respect to the axis. For example, such a sensor assemblymay be coupled to and or located near an axis of rotation of theprosthesis 700.

With reference to FIG. 20, the illustrated lower limb prosthesis 700comprises a foot member 702 connectable by screws 703 to a heel member704. As shown, the foot member 702 and heel member 704 may comprise afoot unit, such as an LP VARI-FLEX® prosthetic foot commerciallyavailable from Össur. In yet other embodiments, the foot member 702and/or heel member 704 may take on other configurations, or the lowerlimb prosthesis 700 may operate without a heel member 704.

As illustrated, the foot member 702 is configured to rotatably attach toa main frame 706, or attachment member, about a main pivot pin 708extending through a base part 710. In certain embodiments, the mainpivot pin 708 and the base part 710 form a pivot assembly that isconfigured to substantially mimic the natural motion of a healthy humanankle. For example, the main pivot pin 708 may allow for dorsiflexionand plantarflexion of the foot member 702, as is described in moredetail previously with respect to the prosthesis 100 of FIGS. 1-6.

The prosthesis 700 further includes an actuator 712 operatively coupledto the foot member 702 through the base part 710. In particular, theactuator 712 couples to a lower pin 714 that allows for rotation of abottom portion of the actuator 712 with respect to the base part 710secured to a top, rear portion of the foot member 702. In certainembodiments, the actuator 712 is advantageously capable of adjusting atleast one angle between the main frame 706 and the foot member 702, suchthat the foot member 702 rotates about the main pivot pin 708 of thepivot assembly. In certain embodiments, the actuator 712 comprises anyone of the various types of actuators disclosed herein and is capableadjusting the angle between the main frame 706 and the foot member 702based on one or more signals received from an electronic control system.

As shown in FIG. 20, the lower limb prosthesis 700 optionally furtherincludes a keypad 716 to receive user input and a rear cover 718 thatpartially covers the actuator 712. The prosthesis 700 may also includeother devices and/or couplings to facilitate attachment of theprosthesis 700 to a limb, such as a stump, of an amputee.

The illustrated lower limb prosthesis 700 further includes a sensorassembly 720 configured to couple to and extend through the base part710 of the pivot assembly. In certain embodiments, the sensor assembly720 is configured to measure movement of at least one portion of theprosthesis 700 in at least one direction. In certain preferredembodiments, the sensor assembly 720 is configured and positioned tomeasure movement of a portion of the prosthesis 700 in a singledirection.

For example, as illustrated in FIG. 20, at least a portion of the sensorassembly 720 is positioned within the main pivot pin 708 and extendsalong an axis (e.g., a pivot axis) substantially perpendicular to alongitudinal, or vertical, axis of the main frame 706. The illustratedsensor assembly 720 is capable of detecting, or measuring, rotation ofthe foot member 702 about the axis of the main pivot pin 708.Furthermore, in certain embodiments, the sensor assembly 720 is securedto the pivot assembly of the prosthesis 700 such that the sensormeasurements are not affected by loads or forces in directions otherthan rotation about the main pivot pin 708. For example, in certainembodiments, axial or radial movements with respect to the axis of themain pivot pin 708 do not affect the measurements of the sensor assembly720.

FIG. 21 illustrates a disassembled view showing further details of thecomponents of the sensor assembly 720 of FIG. 20. As shown, the sensorassembly 720 includes a displacement measurement sensor 722 coupled toan elongated bellow portion 724 through an extender portion 726. Incertain embodiments, relative rotation of the foot member 702 withrespect to the main frame 706 is measured by the displacementmeasurement sensor 722.

Measurements of such rotation may be performed by the sensor assembly720 in several ways. In certain embodiments, the main pivot pin 708 isrigidly attached to the base part 710, and the elongated bellow portion724 is positioned at least partially within the main pivot pin 708. Insuch embodiments, relative movement of the foot member 702 (and attachedbase part 710 ) with respect to the main frame 706 causes relativerotation between the elongated bellow portion 724 (and attached extenderportion 726 ) with respect to the displacement measurement sensor 722.For instance, rotation of the foot member 702 may cause rotation of theelongated bellow portion 724 with respect to the displacementmeasurement sensor 722, which may be fixed with respect to the mainframe 706. In other embodiments, rotation of the foot member 702 maycause rotation of the displacement measurement sensor 722 with respectto the elongated bellow portion 722, which may be fixed with respect tothe main frame 706.

In certain embodiments, the displacement measurement sensor 722comprises a potentiometer, such as, for example, a linear or logarithmicpotentiometer. In such embodiments, rotation of the elongated bellowportion 724 causes a corresponding rotation of the extender portion 726and a rotatable input 727 of the potentiometer. In yet otherembodiments, other types of displacement measurement sensors may beused, such as, for example, rotational position transducers, optical ormechanical encoders, combinations of the same or the like, to measuremovement and/or rotation of a component of the prosthesis 700.

As illustrated in FIG. 21, the elongated bellow portion 724 furtherincludes a plurality of ridges 728 around an outside surface of thebellow portion 724. In certain embodiments, the ridges 728advantageously eliminate or substantially reduce the effects of axial(e.g., along the axis of the bellow portion 724) and/or radial (e.g., adirection perpendicular to the axis of the bellow portion 724) movementsand/or loads on measurements by the displacement measurement sensor 722.For instance, at least some of the ridges 728 may be located within acomponent housing at least a portion of the elongated bellow portion724. In certain preferred embodiments, such a component may include themain pivot pin 708 depicted in FIG. 20. In such embodiments, the ridges728 may advantageously isolate movement of the elongated bellow portion724 to rotation about the axis of the elongated bellow portion 724 andthe main pivot pin 708.

In yet other embodiments, the elongated bellow portion 724 may include aplurality of grooves or other surface features that isolate movement ofthe elongated bellow portion 724 to a single direction. In yet otherembodiments, the sensor assembly 720 may function without the extenderportion 726 or the ridges 728. For example, the sensor assembly 720 mayinclude a flexible compression membrane that couples the displacementmeasurement sensor 722 to the main pivot pin 708 and that absorbsunwanted movement (e.g., axial and/or radial movement).

Although the sensor assembly 720 has been described with reference toparticular embodiments, other configurations for the sensor assembly 702may be used with the prosthesis 700. For example, the main pivot pin 708may be rigidly attached to the main frame 706. In such embodiments,either the displacement sensor 722 or the elongated bellow portion 724may also be affixed to the main frame 706 such that relative movement ofthe foot member 702 with respect to the main frame 706 is detected bythe displacement measurement sensor 722.

In yet other embodiments of the invention, the prosthesis 700 mayinclude other types of sensor assemblies usable to detect movement of atleast one component of the prosthesis 700. For example, the prosthesis700 may comprise a ball joint assembly that has its movement constrainedin at least one direction by geometric constraints surrounding the balljoint, which constraints may include, for example, one or more pins orflat surfaces that engage one or more surfaces of the ball joint. In yetother embodiments, the sensor assembly 720 may include a flexiblematerial that is stiff against twisting forces but allows forlongitudinal compression and/or radial movement.

Furthermore, it will be understood that the sensor assembly and/orprosthesis 700 may advantageously used with a variety ofmotion-controlled prosthetic and/or orthotic devices, examples of whichare described in more detail herein and in U.S. patent application Ser.No. 11/056,344, filed on Feb. 11, 2005, and entitled “SYSTEM AND METHODFOR MOTION-CONTROLLED FOOT UNIT,” which is hereby incorporated byreference herein in its entirety and is to be considered a part of thisspecification.

While certain embodiments of the inventions have been described, theseembodiments have been presented by way of example only, and are notintended to limit the scope of the inventions. Indeed, the novel methodsand systems described herein may be embodied in a variety of otherforms. For example, the foregoing may be applied to the motion-controlof joints other than the ankle, such as a knee or a shoulder.Furthermore, various omissions, substitutions and changes in the form ofthe methods and systems described herein may be made without departingfrom the spirit of the inventions. The accompanying claims and theirequivalents are intended to cover such forms or modifications as wouldfall within the scope and spirit of the inventions.

1. A system for sensing a rotational movement of a lower-limb prostheticdevice, the system comprising: a prosthetic foot; an attachment memberhaving an upper end and a lower end; a pivot assembly rotatably couplingthe lower end of the attachment member to the prosthetic foot to allowfor rotation of the prosthetic foot about a pivot axis extending throughthe pivot assembly, wherein the pivot assembly is configured tosubstantially mimic a natural ankle joint; and a sensor assembly coupledto the pivot assembly and configured to detect the rotation of theprosthetic foot about the pivot axis, wherein at least a portion of thesensor assembly is configured to rotate about the pivot axis and issecurely positioned along the pivot axis to substantially eliminateother movement.
 2. The system of claim 1, wherein the sensor assemblycomprises a displacement measurement sensor configured to output asignal indicative of the rotation of the rotatable portion of the sensorassembly.
 3. The system of claim 2, wherein the displacement measurementsensor comprises a potentiometer.
 4. The system of claim 2, wherein therotatable portion of the sensor assembly comprises an elongated bodythat substantially extends along the pivot axis.
 5. The system of claim4, wherein the rotatable portion of the sensor assembly comprises abellow portion.
 6. The system of claim 5, wherein the bellow portion isconfigured to at least partially fit within a hollow pivot pinsubstantially extending along the pivot axis.
 7. The system of claim 6,wherein the bellow portion comprises a plurality of ridges configured tolimit movement of the bellow portion to rotation about the pivot axis.8. A system for sensing a rotational movement of a device associatedwith a limb, the system comprising: a foot unit; an attachment memberhaving an upper end and a lower end; a pivot assembly rotatably couplingthe lower end of the attachment member to the foot unit to allow forrotation of the foot unit about an axis extending through the pivotassembly, wherein the pivot assembly is configured to substantiallymimic a natural ankle joint; and a sensor assembly coupled to the pivotassembly and configured to detect the rotation of the foot unit aboutthe axis and to substantially neglect axial and radial movement of thefoot unit with respect to the axis.
 9. The system of claim 8, whereinthe sensor assembly further comprises a potentiometer.
 10. The system ofclaim 9, wherein the sensor assembly further comprises an elongatedbellow portion coupled to the potentiometer, wherein the elongatedbellow portion substantially extends along the axis.
 11. The system ofclaim 10, wherein the elongated bellow portion substantially restrictsmovement to rotation about the axis.
 12. The system of claim 10, whereinthe pivot assembly comprises a cylindrical pivot pin extending along theaxis and configured to house at least a portion of the elongated bellowportion.
 13. The system of claim 8, wherein the pivot assembly comprisesa housing and a ball joint movable within the housing.
 14. The system ofclaim 13, wherein the housing restricts movement of the ball joint torotation about the axis.
 15. The system of claim 8, wherein the footunit comprises at least one of a prosthesis and an orthosis.
 16. Thesystem of claim 8, further comprising an actuator configured to adjustthe attachment member and the foot unit about the pivot assembly. 17.The system of claim 16, wherein the actuator is configured to activelyadjust an angle between the attachment member and the foot unit.
 18. Asystem for sensing a rotational movement of a device associated with alower limb, the system comprising: a foot means for contacting a groundsurface; a means for attaching the foot means to a patient; a means forpivotably coupling the foot means to a lower end of the means forattaching to allow for rotation of the foot means about an axisextending through the means for pivotably coupling, wherein the meansfor pivotably coupling substantially mimics an ankle joint; and a meansfor sensing coupled to the means for pivotably coupling, the means forsensing further configured to detect the rotation of the foot meansabout the axis and to substantially neglect axial and radial movement ofthe foot means with respect to the axis.
 19. The system of claim 18,wherein the means for sensing comprises a potentiometer.
 20. The systemof claim 19, wherein the means for sensing comprises an elongated bellowportion coupled to the potentiometer, wherein the elongated bellowportion is configured to restrict movement of the foot means to rotationabout the pivot axis.